As I promised in my previous post, I will dedicate this article to a relatively recent invention in the field of pulse oximetry: the T-stat oximeter.
As its name suggests, it is still an oximeter (a blood oxygen monitor), but it has improved functions.
What does this new oxygen monitor do and why was its invention necessary?
Traditional oxygen monitors have one big blind spot: they can determine the percentage of saturated hemoglobin only by relying on the pulsing of the blood vessels. If the pulse ceases (for example, such a scenario happens during bypass surgeries), pulse oximeters are of little use and specialists cannot determine if the patient has an adequate oxygen supply. Pulse oximetry also fails to detect oxygen saturation if the blood flow is weak or obstructed – even if the pulmonary functions of the patient are normal.
The new T-Stat oximeter – invented in the beginning of the ‘2000 by the Stanford professor David Benaron, M.D. – is a Visible Light Spectroscopy (VLS) system that monitors the blood oxygen levels in microvascular tissues. If the traditional pulse oximeter’s readings are indicated as a SpO2 percentage, the new T-Stat oximeter displays a StO2 percentage.
The T-Stat oxygen monitor focuses on the amount of oxygen that reaches small capillaries, even when the blood flow is weak, obstructed or there is no pulse at all. It is non-invasive as well, and it works (just like the pulse oximeter) by interpreting the blood color: however, if the pulse oximeter uses red and infrared light frequencies to measure the ratio of saturated to unsaturated hemoglobin, the new monitor makes use of shorter wavelengths – green and blue. These light waves can monitor specific tissues (the smallest blood vessels – capillaries) and detect the oxygen levels in that spot.
This device consists of a main electronic monitor and a sensor probe. The monitor collects the data, analyses it and displays the results. The sensor emits light frequencies that illuminate the specific tissue which needs to be studied. When it is returned to the monitor, the reflected light is analyzed and the StO2 estimated.
The T-Stat Tissue Oximeter is FDA approved. It is used as an additional source of information whenever the oxygen saturation readings provided by the pulse oximeter are insufficient or inadequate for determining the patient’s condition. The T-Stat monitor can measure the blood oxygen saturation in specific microvascular tissue spaces in infants, children and adults that present a risk of ischemic states (ischemia is a medical term that describes a restriction in blood supply to a certain area of the body, usually as a consequence of blood vessels damage).
Because of its capabilities of offering such detailed readings and monitoring ischemic states, this type of oxygen monitor is used only in clinical care and in operating rooms, especially during vascular surgery. The inventor of the T-Stat monitor, Dr. Benaron, is hoping that in the near future his invention will prove its efficiency in diagnosing other dysfunctions, especially cancer (since tumor cells usually have lower levels of oxygen as compared to normal cells).